CAULE: função, estrutura e tipos | RESUMO DE BOTÂNICA - BIOLOGIA PARA O ENEM. Profa Claudia Aguiar

🎓 Free Enem Course: https://goo.gl/2rebsa 📑 Full summary: https://bit.ly/3oYnPKq ✔️ Mock exam: https://bit.ly/38L4rsj Subscribe to the channel to receive everything about the Enem 100% FREE https://bit.ly/37WGBZi #biology #plants #stem /// ABOUT THE VIDEO STEM: function, structure, and types | BOTANY SUMMARY - BIOLOGY FOR THE ENEM. Watch with Professor Claudia Aguiar, from the Free Enem Course. Perhaps, right now, you are sitting on a wooden chair or your computer is on a wooden table. The wood used as the raw material for these pieces of furniture comes from the stems of some plants. But, although we generally think of stems as woody structures, stems have different morphologies and functions. The stem is a structure that generally supports the aerial parts, especially the leaves. Because it commonly grows toward the sky, the stem allows the leaves to receive better lighting conditions, facilitating photosynthesis. Inside the stem, we find both tissues that support its structure and conducting vessels. These vessels carry raw sap from the roots to the leaves (xylem vessels) and also from the leaves to the roots (phloem vessels). Stems can also act as energy storage structures, as in potatoes. Or, even as water storage structures, as in cacti. Finally, some stems can also perform photosynthesis, as occurs in young plants. In general, stems exhibit positive phototropism. This means that they tend to grow toward light. At the same time, stems also exhibit negative gravitropism, meaning they grow in the opposite direction to the acceleration of gravity. Also called the terminal bud or vegetative point, the apical bud is a zone of height growth in the plant. In the apical bud, we find the primary meristem, with undifferentiated cells that multiply to increase the size of the plant and then differentiate. In these meristems, leaf primordia emerge—small protuberances that sit at the tip of the stem, protecting the apical bud and which later form the leaves. In the leaf axils, we find structures called lateral buds or auxiliary buds. They contain meristematic tissues that will give rise to the lateral branches (twigs) of the plant. These buds, during the initial development of plants, are generally dormant. After a certain period of development, the lateral buds are activated and begin to develop into branches. We call the region of the stem where the lateral bud is located a node. Internodes are the regions of the stem located between two nodes. We can observe the primary structure of stems when we make a cross-section of a younger region of the stem. Externally, their primary structure is covered by the epidermis. Internally, we commonly find chlorophyll parenchyma, since these stems also commonly initially carry out photosynthesis. Internally, we commonly find supporting tissues, such as collenchyma. Despite the structure described above, in monocotyledonous plants and herbaceous dicotyledons, there is no significant differentiation between the stem cortex and its central cylinder. This is because the vascular bundles in these plants spread throughout the stem, organized concentrically within the ground parenchyma. Another important factor about these bundles is that they are mixed. In other words, these vascular bundles contain both woody (xylem) and bast (phloem) vessels, organized into a single bundle. It's clear that the bast vessels all face the outside of the stem, while the wood, on the other hand, faces the inside. In the vast majority of dicotyledons, the vascular bundles are arranged in a ring shape, organized around a pith of parenchymal tissue. The vascular bundles in these plants are also bast-woody (containing both xylem and phloem). However, between the two types of vessels, we find the fascicular cambium. In these dicotyledons, we can also see differences between the stem cortex and its pith. In this class, Professor Claudia Aguiar will show you the functions, structure, and types of stems. Questions? Leave them in the comments. ;) ⏱ TIMESTAMPS / TOPICS 00:00 Main characteristics of the stem 01:59 Stem structure 03:21 Internal morphology of the stem 07:18 Stem types 🔴 WATCH ALSO Kingdom plantae    • REINO PLANTAE E SUAS CARACTERÍSTICAS | Res...   ❤️ SOCIAL MEDIA INSTA @cursoenemgratuito TWITTER @enemgratuito FACEBOOK /cursoenemgratuito/ // AFTER ALL, WHAT IS THE FREE ENEM COURSE? We are a channel with completely free classes on the topics most frequently asked on the ENEM and university entrance exams. Want to study with us? 🎓 ACCESS OUR 100% FREE ENEM COURSE https://goo.gl/2rebsa